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LPC11u68 Expresso Board Hold Pin Low During Power Up

Question asked by Dustin Hagstrom on Dec 5, 2017
Latest reply on Dec 7, 2017 by jeremyzhou

Hello all, 


I have an LPC11u68 LpcExpresso board and I have uploaded the attached cpp file (via creating a new project and verifying it runs correctly).  My program wishes to hold a pin low even through power cycles of the LPC board.  As you can see from the attached sketch I have put a pulldown via pin muxing on pin 1_18 and I tell the system to make it output low.


The problem is, when I power up the board there is a very brief period where the pin goes high just as the power goes high, then the pin goes low as it should.  Is there a way to keep that pin low even during power application to the board?  It is a requirement for a project I am working on.  


In the attached scope shot, the (Yellow) Channel 1 is pin 1_18 and the (Blue) Channel 2 is the 3.3V line to show when power is applied.


Thank you for your help,